This application relates to new and improved sabots which have reduced friction and can be fired at higher velocities. More specifically this invention relates to thermoplastic sabots containing a solid lubricant filler which reduces friction between the sabot and the bore of the firearm through which it is fired.
There is much literature regarding the use of plastic sabots in rifled firearms and particularly rifles. In general these sabots are deformable and act as a sealant to prevent gases from leaking out the barrel ahead of the bullet and sabot. These gases, resulting from the firing of a cartridge, propel the sub-caliber bullet forward with greater velocity than they do a full caliber bullet. Various types of plastics have been used such as polycarbonates, polyamides (nylons), fluorocarbons, acrylic polymers, acetal resins and polyalkylene polymers such as high density polyethylene.
Prior art sabots are generally cylindrical in shape with the front and back ends being of substantially the same diameter and containing blunt ends. The front portion of the sabots are generally scored or contain external grooves or other devices to weaken the sabot structure. The air resistance against the blunt forward end of the rotating sabot and the centrifugal force exerted on it as it emerges from the firearm barrel causes the sabot to rupture at the weakened areas thus releasing the projectile. Typical sabots having these characteristics are taught in U.S. Pat. Nos. 2,820,412; 3,005,804; 3,141,412; 3,164,092; 3,186,342 and 3,317,061.
In police work and other types of protective activities, it is often necessary to utilize armor piercing projectiles. It would be desirable to be able to fire such projectiles from pistols. Such materials as case hardened steel are desired projectiles but a full caliber projectile made of such hardness would soon score the lands and ruin the riflings within a gun barrel. It is also desirable to obtain maximum velocity when firing such projectiles. It is known that such hardened projectiles can be fired from a rifle in sub-caliber form using a sabot to optimize velocity without building up gas pressures that would be harmful to the firearm or the shooter and to avoid damage to the riflings. However, projectiles fired from prior art plastic sabots are somewhat slowed in the barrel due to friction and are further slowed by the wind resistance encountered at the blunt foreward end of the sabot after it emerges from the muzzle of the firearm but before separation of the bullet from the sabot. The blunt end of the prior art sabots also create a problem in that they often interfere with the loading mechanism of the firearm causing it to jam.